Micrometer-gage.



No. 886,817t

PATENTED MAY 5, 1908. C. A, KELLEY. MIGROMETER GAGE. APPLICATION FILEDJUNE 2o. I9o7.

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CHARLES A. KELLEY, OF SPRING LAKE, MICHIGAN.

MICROME TER-GA GE Specication of Letters Patent.

Patented May 5, 1908.

Application filed June 20,1907. Serial No. 379,905.

To all whom it may concern:

Be it known that I, CHARLES A. KELLEY, a citizen of the United States,and a resident of Spring Lake, in the county of Ottawa and State ofMichigan, have invented an Improved Micrometer-Gage, of which thefollowing is a speciiication.

My invention is a caliper of that type in which the frame is U-shape anda micrometer screw is adapted to rotate in a nut, or threaded sleeve,fixed in one end of said frame whereby the tip of the screw may beadjusted toward and from the other end of the frame for ascertainingvarious diameters.

My object is to provide such a caliper or micrometer gage, which isgraduated in such manner that it may be read more easily and quicklythan others of its class, the graduations being most convenientlyexpressed in eths of an inch upon the rotatable thimble rigidlyconnected with the micrometer screw constituting one of the gagingpoints of the instrument.

The features embodying my invention are as hereinafter described, andillustrated in the accompanying drawing, in which Figure 1 is a sideview of my improved caliper. Fig. 2 is mainly alongitudinal section ofsame. Fig. 3 is a plan view of the rotatable thimble as extended in theiiat, with the rows of numerals thereon expressing differentgraduations. Fig. 4 is a plan view of the scales orgraduations on thesleeve extended in the iiat. Fig. 5 is a diagrammatic view illustratingthe method of determining measurements by the use of my improvedcaliper.

A indicates the U frame, B the micrometer screw, C a sleeve nut, orthreaded hub, iixed in one end of said frame and in which the screw isadapted to rotate for adjusting it toward and from the abutment screw Dheld in the other end of said frame. The screw B is formed integral, orotherwise rigidly connected, with the thimble E whose annular chamber isadapted to receive the sleeve C and is thus adjustable together with thescrew B. As such calipers are usually constructed, the pitch of themicrometer screw is forty to the inch, and the sleeve C is graduatedcorrespondingly as at c, see Figs. 1 and 4, while the beveled inner endof the thimble E is graduated into twenty-five parts and figured toindicate every five divisions, as O, 5, 10, 15, 20. Thus, each divisionwhen passing the line of graduation on the hub, indicates that the screwhas made 1/25 of a turn and the opening of the caliper increases 1/25 of1/40 or 1/1000'of an inch. Hence,

to read such caliper in thousandths of an inch it is necessary tomultiply the number of divisions visible on the scale of the hub orsleeve C by 25 and add the number of divi-v sions on the scale of thethimble E from zero to the line coincident with the line of graduationson the sleeve.

I have devised an improvement in such calipers whereby fine graduationsmay be employed and read instantly without the necessity of any mentalcalculation. To attain this result I graduate the sleeve C, as indicatedin Figs. 1, 4, 5, in 64ths of an inch, and I provide the thimble E witha series of longitudinal lines parallel to its axis and withcorresponding rows of numerals which are so related to (S4-scalegra'duations on the sleeve C that any adjustment of the screw B may beinstantly read in 64ths or 32nds of an inch, or any multiple of it. Thebase or first line on the thimble E is indicated and to be known as zero(0), and the other lines are distant from it by regular spaces. Thus thesecond line is of the circumference of the thimble, the third line thefourth line the iifth line of the circumference, the sixth line theseventh line and the 8th line of the circumference. As is wellunderstood, by turning the thimble E until its beveled end comes exactlyover the 64th graduation on the sleeve C one of the long lines indiicated on E will coincide with the base line c2 of the graduations on thesleeve, and then by inspection of the numbers extended along the line ofthe thimble, the exact measurement in 64ths of an inch may beascertained, and without mental calculation or reference to a conversiontable.

While approximate readings in 64ths of an inch may be obtained by thegraduations on the sleeve C, as indicated at c', Figs. 1, 4 and 5, as onan ordinary inch scale, the exact readings in 64ths may be obtained onlyby reference to the graduations indicated in the several rows on thethimble E; see Figs. 1 and 3. There are but eight places on the thimblewhich coincide with the axial gradu 10.5

line, the 64ths, 32nds, lths, or Sths for which that line may be usedbeing marked thereon. Thus, the line on the thimble E which could beused for the exact reading of 15/32 would appear thus:

That same line then would be used for 32 32 32 32 32 32 32 If now it bedesired to measure accurately it is irst read off on an ordinary inchscale on the sleeve C by rotating the thimble E until its beveled edgecomes exactly over that graduation, and then it will be found that theaxial line indicated by e (Figs. 1 and 3) on the thimble lies verynearly, or exactly, over the line c2 on the sleeve C. By adjusting thetwo so that the lines lie exactly to- 15 getlier, we have the exactmeasure of 33, or,

what is equivalent, Again, if it be desired to measure of an inch, thethimble E is rotated until its beveled end comes exactly over theAgraduation next after 56. Then the axial line e on the thimble, seeFig. 5, along which the numerals 1, 9, 17, 25, 33, 41, 19, 57 arearranged will coincide with the line c2. I

The new graduations-on the thimble are independent of the old onesindicated by numerals Zero (O) to 20, and may be used equally well withor Without the 4() scale on the hub or sleeve C. There is in no case anymental calculation required for using the instrument in measurement.

What I claim isE 1. The improved micrometer caliper coinprising a Uframe, an internally threaded sleeve fixed in one end of said frame, amicrometer screw adapted for adjustment in said sleeve, a thimblerigidly connected with the screw and adjustable rotatably on the sleeve,the sleeve having graduations in 64ths of an inch extended along thebase line, and a thimble having axial lines dividing it into regularcircumferential spaces, and a series of corresponding rows of numeralsfor all the said lines saving the base or zero line, such numeralsindicating fractional parts of an inch in 64ths so that when the thimbleis rotated and the screw adjusted for certain measurements, an accurateindication thereof may be instantly read on the thimble on the axialline thereof, which then coincides CHARLES A, KELLEY.

Witnesses:

WILLIAM G. LELAND, JOHN B. PRUIM.

